1. Field of the Invention
The present invention relates to a golf club and, especially, relates to a golf club whose characteristics such as the lie angle, slice angle and face progression can be adjusted easily. Also, the invention relates to a method for adjusting the characteristics of such golf club.
2. Description of the Related Art
A golf club is constituted of a shaft and a head mounted on the leading end portion of the shaft. A grip is mounted on the base end side of the shaft.
In an ordinary conventional golf club head, a hosel hole is formed directly in the head, while a shaft is inserted into the hosel hole and is fixed thereto with an adhesive. Here, as the adhesive, generally, there is used an epoxy system adhesive. To replace the shaft, the hosel portion may be heated to destroy its texture constituted of epoxy resin hardened material, whereby the shaft can be pulled out.
In such ordinary conventional golf club, the shaft replacement takes time and labor. Also, the characteristics of the golf club such as the lie angle, slice angle and face progression cannot be adjusted.
JP-A-2011-4801 discloses a golf club whose shaft can be replaced easily and whose characteristics such as the lie angle, slice angle and face progression can be adjusted, and a method for adjusting such characteristics. The head of the golf club disclosed in JP-A-2011-4801 is a golf club head including a hosel insertion hole for mounting the leading end of the shaft, which includes a female screw formed in the entrance portion inner peripheral surface of the hosel insertion hole, a hosel including a shaft case insertion hole and removably mounted on the deep portion of the hosel insertion hole, a shaft case including a shaft insertion hole and having a leading end side removably mounted into the shaft case insertion hole, a ring holder fitted with the outer surface of the shaft case and immovable in the axial direction, and a screw member fitted with the outer surface of the ring holder rotatably in the peripheral direction and immovable in the axial direction, while a male screw formed on the outer peripheral surface of the screw member is threadedly engaged with the female screw.
In the golf club disclosed in JP-A-2011-4801, by mounting the screw member onto the female screw of the hosel mounting hole or removing the screw member therefrom, the shaft case can be fixed to or pulled out from the hosel mounting hole. Thus, the hosel and ring holder are replaced with other hosel and ring holder different in the lie angle, slice angle or face progression, or the peripheral direction phase of the hosel is changed, and the shaft case with a shaft is mounted again onto the head main body through this hosel.
For example, when the currently used hosel and ring holder are replaced with new hosel and ring holder in which the axis of its shaft extends in a direction oblique to the axis of the hosel insertion hole (for example, in an obliquely crossing direction), the mounting direction of the shaft relative to the head main body is changed to thereby change the lie angle and slice angle.
In a golf club constituted of quite the same shaft and the same head main body, only the lie angle and slice angle can be adjusted.
Also, in the case that the current hosel and ring holder are replaced with new hosel and ring holder in which the axis position of the shaft case insertion hole is translated and shifted from the axis position of the hosel insertion hole, in a golf club constituted of quite the same shaft and the same head main body, the face progression and the distance (gravity distance) from the shaft to the center of gravity can be adjusted.
Further, in JP-A-2011-4801, by replacing the shaft with a shaft case without replacing the hosel and ring holder, the shaft can be replaced. That is, as a shaft case, a shaft case of quite the same type is previously prepared, and a shaft having a different characteristic is fixed to this shaft case to thereby provide a shaft case/shaft connected member; and, this shaft case/shaft connected member is substituted for an old shaft case/shaft connected member and is mounted on the hosel of the relevant head, thereby being able to provide a golf club different only in the shaft.
The golf club disclosed in JP-A-2011-4801 requires the ring holder fitted with the outer surface of the shaft case and the screw member fitted with the outer surface of the ring holder, resulting in the relatively expensive cost of the composing members.